NOx storage/reduction over alkali-metal-nitrate impregnated titanate nanobelt catalysts and investigation of alkali metal cation migration using XPS

We reported earlier that KNO3- and Pt-impregnated potassium titanate nanobelt (KTN) catalysts exhibit high storage capacity and excellent catalytic cycles for NOx storage-reduction (NSR) reaction. In the present study, we compared the NSR behavior of various alkali-metal-nitrate impregnated KTN catalysts, which revealed that the KNO3-impregnated catalyst exhibited superior performance. The XPS and XRD analyses of the NaNO3-impregnated KTN catalyst showed that the migration of K+ from KTN bulk to the surface nitrate salt took place more predominantly than the migration of Na+. Probably for this reason, KNO3-impregnated KTN materials exhibit the best performance for NSR catalytic cycles.

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► The NSR activity of KTN was enhanced by the decoration of various alkali nitrates.
► NaNO3 impregnated one showed comparably better activity to KNO3 impregnated one.
► Migration of K+ from KTN bulk to surface nitrate salts is a key step for NOx storage.